To consider what director Kathryn Bigelow has accomplished in "Zero Dark Thirty," imagine the events depicted by the story if they'd been given the "Argo" treatment.

Not to take anything away from that rousing true (-ish) story of hostages freed and rights wronged and, in every sense, Hollywood triumphant. But think about it. If Ben Affleck or a lesser Ben Affleck had directed "Zero Dark Thirty," a film concluding with the raid on Osama bin Laden's compound in Abbottabad, Pakistan, nearly a decade following the deadly attacks of Sept. 11, 2001, we'd have been led down a very different moviegoing path.

In "Zero Dark Thirty," the key American film of 2012, now going into wider release, Bigelow and screenwriter Mark Boal — the pair behind "The Hurt Locker" — are after something truer and more lasting than getting an audience to burst into applause when the bad guys are outfoxed. Nothing in the climax of "Zero Dark Thirty" settles for easy triumphalism. Everything about the film is potentially controversial, yet hardly any of it can be pigeonholed by way of ideology or politics.

The raid on bin Laden's compound, much of it filmed through an approximation of night-vision goggles, necessarily sidelines the film's main character, Central Intelligence Agency operative Maya, played by Jessica Chastain. This is an odd thing for a movie, even a fact-based movie, to do to its protagonist. It is also the honest thing. With the same bittersweet artistry Bigelow and company lend their prologue, we return, briefly, to the main character's wary and exhausted company after the raid. She is a heroine (conflicted, perhaps; how conflicted is up to the viewer) behind the heroes.

The prologue begins in darkness, and then fades into panicked voices. In a brilliant sound collage of telephone conversations back and forth from those trapped in the World Trade Center towers, the horror of that morning comes rushing back. Then, quickly, we're in Pakistan. Maya is the new kid in town, learning enhanced interrogation techniques (torture by any other name) and other tricks of the trade from her fellow CIA operative, played by Jason Clarke. "There's no shame if you want to watch through the monitor," he tells her. She declines. The waterboarding begins. "Zero Dark Thirty," its title taken from military phraseology for 12:30 a.m., is our monitor, the prism through which we see this world.

We know little of Maya's past, just as we knew little of the bomb detonation expert played by Jeremy Renner in "The Hurt Locker." Bigelow and Boal are interested in the present tense, and experiences rather than explanations. As a tough, old-school CIA operative, the marvelous Jennifer Ehle shares a scene in a hotel bar with Chastain that hints at Maya's obsessive nature and blinkered personality. The way that scene ends is the essence of this coolly startling picture, one devoted to intelligence gathering of various methods, some effective, some amoral, under the most volatile imaginable conditions.

Bigelow casts all sorts of solid and familiar actors in all sorts of roles, including Kyle Chandler as the CIA's Islamabad overseer, trying to decide which of his employees' hunches to take most seriously. The Navy SEALs who enter the action in the final round are played by, among others, Joel Edgerton and Chris Pratt. As for Chastain, she is by now a full-on movie star, as well as an unusually versatile and gifted actress. Hers may be a largely reactive role, but on screen Chastain can do almost anything. Better than that, she understands how much is needed in any given encounter. Here, less is enough.

The naturalistic style of the picture owes a lot to the Olivier Assayas terrorist film "Carlos," and the actor who played the title character in that picture, Edgar Ramirez, shows up here as one of Maya's skeptical colleagues. Bigelow, a master of complicated lines and crosscurrents of physical action, doesn't treat everything leading up to the raid as a preamble or a necessary evil. The lead-up is, after all, the majority of the film. We move from one country to another, from one CIA "black site" to another, with Maya's frustrations guiding the narrative. The years and the casualties mount.

Events depicted in the film, notably the waterboarding, have been debated from every side, both for their factual accuracy (not that anyone's complaining about the hogwash content in "Argo") and their political implications. I assure you: Although "Zero Dark Thirty" ends with the sight of a (metaphorical) bloodstained flag behind its elusive protagonist, its stance is extremely tricky. It's not a documentary. It's not a load of revenge nonsense. It's not "24." I'm still arguing with myself over parts of it.